(1) Field of the Invention
The present invention relates generally to underwater load cells, and more particularly to a optical load cell that detects movement of a body underwater.
(2) Description of the Prior Art
Load cells or shear webs are used in a variety of underwater drag test applications. Briefly, these devices are types of strain gauges that measure movement of an object underwater due to a fluid flow moving thereover. While these devices are suitable for some applications, they are unreliable when used in the presence of high electric currents. Specifically, since the strain gauges operate on very low current, the presence of high current levels can electrically interfere with the low current strain gauges. For example, high current levels are present when underwater drag tests are performed on electrically-powered exterior panels that make up part of a magneto-hydrodrive propulsion system.
Accordingly, it is an object of the present invention to provide a load cell device that is insensitive to the presence of high electric current levels.
Another object of the present invention is to provide load cell device that can operate underwater.
Still another object of the present invention is to provide a load cell device that can be adjusted from a remote location in order to avoid unwanted disturbances in a surrounding fluid flow.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, a system is provided for detecting movement of an object underwater. A housing positioned underwater defines a gas-filled cavity. An optical reflector is fixedly coupled to an object underwater. A portion of the optical reflector is positioned in the cavity. At least one optical sensor is provided with each optical sensor having a body portion coupled to an optical sensing portion. An adjustable positioning system positions the optical sensing portion in the cavity a desired distance from the optical reflector. Movement of the object underwater causes movement of the optical reflector that is detected by the optical sensing portion.